Charged particle beam apparatuses have many functions in a plurality of industrial fields, including, but not limited to, inspection of semiconductor devices during manufacturing, exposure systems for lithography, detecting devices and testing systems. Thus, there is a high demand for structuring and inspecting specimens within the micrometer and nanometer scale.
Micrometer and nanometer scale process control, inspection or structuring is often done with charged particle beams, e.g. electron beams, which are generated and focused in charged particle beam devices, such as electron microscopes or electron beam pattern generators. Charged particle beams offer superior spatial resolution compared to, e.g. photon beams, due to their short wavelengths.
Thereby, charged particle beam devices, in particular systems for accurate measurements like CD measurement systems in chip industry, EDX in material analysis, or the like, have a desire for a defined beam current. Furthermore, quantitative measurements require a stable beam current. Standard systems use a Faraday cup connected to an electrometer in order to measure the beam current on a regular basis. Thereby, during periodic maintenance, e.g., on a daily basis, the beam current is measured and readjusted to the required value. This process is time-consuming and unacceptable if the operation of the charged particle beam device should not be interrupted for a long time or if the beam current measurement should be conducted more frequently.